A memory array comprises a plurality of tiny rings called cores of ferromagnetic material a few hundredths of an inch in diameter. The cores are usually arranged in rows and columns and coordinate leads designated X and Y leads are employed to address a selected core in the matrix. The cores are strung on a wire and a strong electrical current is sent through the wire in order to magnetize them. The direction of current determines the polarity or magnetic state of the core. By reversing the direction of current the magnetic state of the core is changed. Consequently, the two states of the core can be used to represent 0 or 1, plus or minus, yes or no, or on-or-off conditions. For computer purposes this is the basis of the binary system of storing information.
It is desirable in computer applications that the memory unit have a large storage capacity while requiring minimum space and volume. Other desirable characteristics are low power useage, short cable runs, ruggedness, minimum noise pickup and good heat dissipation. Prior art memory units have been characterized by bulky core memory stacks as well as bulky electronic circuitry to drive and sense the memory stack. In addition, with prior art memory units there was a need for additional solder or connector connections between components plus extra hardware for mounting to standard core memories. Through the use of densely packed memory cores and integrated circuit diode flatpacks plus short wiring techniques, the desirable memory array characteristics are achieved by this invention.